开孔泡沫铝压坑变形的力学行为

Indentation deformation mechanical behavior of open-cell aluminum foams

分别采用圆柱体的平压头应力(FEP)、球面压头(SEP)和圆锥面压头(CEP)3种不同形状的压头对不同参数泡沫纯铝和泡沫Al Si12合金进行了准静态压坑实验,研究了泡沫铝压坑变形的应力随压入深度变化的响应特征,以及相对密度对压坑应力及吸能性的影响。结果表明:平压头压坑的应力-压深曲线由弹性段和应力持续上升的塑性段组成,有明显的屈服点,屈服强度和压坑应力均随密度增加而升高,球面压头和圆锥面压头压坑应力-压深曲线上没有明显的弹性段,只有应力先缓慢上升然后快速升高的塑性段。随相对密度增加和基体强度提高,泡沫铝的压坑应力和吸能性均显著上升。

Quasi-static indentation experiments were carried out on pure aluminum foams and Al Si12 alloy foams with different parameters by using three types of indenter with different end geometries,flat-ended punch（FEP）,spherical-ended punch（SEP） and conical-ended punch（CEP）,respectively.The variation of stress with indentation depth was studied during indention deformation of the aluminum foams,and effects of the relative density on the stress and energy absorption of the foams were investigated.The results show that stressindentation depth curve of the aluminum during FEP indention exhibits two regions including an elastic region and a plateau regime with continuous rise in stress.A distinct yield point is observed on the curve.The yield strength and indention stress of the aluminum foams increase with increasing relative density.The stress-indentation depth curves of the aluminum during SEP and CEP indention are not exhibit distinct yield point.It is found on these curves that stress increases slowly in initial stage and then increases rapidly with the increasing of the indention depth.The indention stress as well as energy absorption of the aluminum foams increase with increasing relative density and strength of the foam matrix.